I just bought my 96 2500 4x4 club cab bone stock 5 weeks ago. The fuel economy is 14mpg steady, it runs rough sometimes and runs better other times. The tranny was just rebuilt 3 weeks ago, I had to change the diff fluid because of popping (and yes I put friction mod. in) I changed the fuel filter, I tested the waste gate (not working) and I can't figure out what's up. It has 160k on it and no mods. From what I've read this truck should run better than this! It does'nt smoke at all except a tiny amount of white in the morn. The exhaust smells ritch all the time. When I changed the f.f. and diff fluid it ran great for about a day. So I put new exhaust gaskets on and that's the last thing I've done. What should I do for more power and mpg's? If the waste gate is not working does that mean I have a boost leak? I don't have guages yet so I'm not sure of egt's/boost. It does have a cat converter by the way but I plan on ordering exhaust soon. I have no idea where to start.

 

I'd get the timing checked, white smoke at startup is an indication of slipped timing. Especially if it seems to "miss" when cold. If they need to set it, have them set it at 14.5* or 15*.
Did you pressurize the wastegate at 30psi? You can't move it by hand.
Overflow valve is another possibility.
Have you checked the intercooler boots?
Also the AFC line from the intake, mine had a bad connection.
I get 19-20 mpg on mine.

 

Hopefuly you didn't invest too much into it yet. Did you test drive it before purchasing?

 

Yea I pulled the waste gate off and put 20 to 25 psi on it and it did'nt move. I put fuel treatment in the tank when I changed the filter. That's when it started running rough. Could I have gel in the tank that clogged the filter? I did check the i.c. boots and they were fine. I don't think it's a fuel thing because it smells ritch all the time but with no smoke. Are these things known for clogged cat conv.? It's not that it runs terrable but I know it's capable of alot more. Any input would help. And by the way I paid 2500 for it, my buddy owns a lot and took it on trade.

 

$2500 for that truck ya done good

 

well 14mpg in the city istn abnormal...white smoke in the morning is normal...if u get snap crackle and pops during morning startups and at higher rpms then u need to get the timing advanced...otherwise id just do fuel filter and a new overflow valve and an oil change...and see what happens

 

oh and drop that cat...could very well be plugged by now and not helping any of the symptoms

 

Well I might have 800-1000 miles on the new fuel filter but I did add the fuel treatment after the change so maby it's cleaning the tank. I'm definatly changing the overflow valve this weekend. Could the overflow cause the over fueling @ idle? It runs fine once you gut going. Thanks for all the help.

 

well its an older diesel with a mechanical pump...white smoke on cold mornings is normal...white smoke does not mean overfueling...thats black smoke...white smoke just means cold cylinders..alot of crackling and popping when u give her gas means low timing....overflow valve has more to do with fuel pressure...and they like to wear out on these pumps and most people never give them a thought until symptoms show up

 

Well my truck smells very ritch @ idle. That's were that question came from. Any ideas on ritch idle. Also does anyone know how many feet of marine fuel line I should buy?